Rig structure



FIG. 1 is a front perspective view of a rig structure showing my new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a rear perspective view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a front elevational view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a rear elevational view thereof. 

CLAIM The ornamental design for a rig structure, as shown and described. 